Production of cigarettes

ABSTRACT

A cigarette filling pressure indicator which, in a preferred arrangement, is arranged to allow the cigarette rod to pass continuously through it before the rod is cut into cigarette lengths. The indicator includes a pressure chamber which compresses an inadequately filled part of the rod, and a comparator device which compares the section of the rod before and after compression so as to detect an inadequate rod filling.

United States Patent Inventors Appl No.

Filed Patented Assignee Priority Frederick Pocock;

Ivan Yehudi Hirsh, both of London, England Jan. 21, 1970 Jan. 11, 1972 Molins Machine Company Limited London, England Jan. 31, 1969 Great Britain PRODUCTION OF CIGARETTES 9 Claims, 4 Drawing Figs.

U.S. Cl 131/21 B, 73/37.7 Int. Cl A24c 5/34, A24c 5/345, GOlb 13/08 Field of Search 73/37-37.8, 38; 131/21 B [56] References Cited UNITED STATES PATENTS 2,792,569 5/1957 Byricett 73/37.5 X 2,952,262 9/1960 Pocock et al. 73/37.7 X

Primary Examiner- Louis R. Prince Assistant Examiner-William A. Henry, ll Attorney-Craig, Antonelli and Hill 2 s 28 z z 26 /4 30 I 8 l l 24 k .4 A

0|APHRAGM l 4 TRANSDUCER 434 EJ ECTO R MECHANISM PATENTEU JAN 1 1 1972 SHEET 1 OF 2 E Fm ZQZSLOME mokuwnw PRODUCTION OF CIGARETTES This invention concerns improvements relating to the production of cigarettes, and is particularly concerned with a method and apparatus for producing cigarettes that are satisfactory to the smoker and are economical in the use of tobacco.

One of the most important objects in the manufacture of cigarettes is to be as economical as possible in using tobacco because of its high price. In modern cigarette manufacture the quantity of tobacco contained in each cigarette is very closely controlled, being limited on the one hand to the minimum which will provide the smoker with a cigarette which he regards as being well-filled, and on the other hand to the maximum amount of tobacco which the cigarette manufacturer can economically afford to put into the cigarettes, while allowing a sufficient margin to ensure that each cigarette is filled satisfactorily. To this end, considerable efforts have been in the past devoted towards reducing to a minimum the variations of the weights of cigarettes produced on any given machine and considerable success has been obtained in reducing these variations to a very low level. However, the level is nevertheless appreciable and there is still room for improvement in economy of the use of the tobacco.

it is an object of the present invention to provide an improved method of controlling the manufacture of cigarettes which will provide satisfactory cigarettes and be economical in the use of tobacco.

A preferred cigarette-making machine according to the present invention includes a tobacco filling indicator including a member defining a pressure chamber with openings through which the cigarette rod passes, means for supplying the pressure chamber with gas (for example air) at a pressure which is sufficient to compress a relatively soft cigarette (i.e., one which is inadequately filled) but is low enough not to damage permanently an adequately filled cigarette, and a comparator for comparing the cross section of the cigarette rod before and immediately after passage through the pressure chamber, and for producing a correction signal when the difference in cross section is above a predetermined amount. A drop in the crosssectional area below a predetermined proportion indicates that the rod at that point is insufiiciently filled. The correction signal may, for example, activate an ejector mechanism which automatically ejects the insufi'iciently filled cigarettes, or it may adjust the tobacco feed to the rod, or it may be capable of initiating both of these actions.

Adjustment of the tobacco feed may in principle take various forms. For example, the adjustment may be achieved by varying steplessly the height of the trimmer as described in any of British Pat. No. 854736/8. Alternatively, the degree of compression of the tobacco before wrapping may be varied automatically in response to the correction signals from the comparator by arranging that the correction signals vary the suction pressure holding the tobacco stream against the perforated band which carries the tobacco stream during trimming.

In one possible arrangement according to this invention the measure of cigarette rod diameter before and after passage through the pressure chamber is obtained by passing the rod through additional precompression and postcompression measurement chambers lying respectively ahead of and behind the pressure chamber, in relation to movement of the cigarette rod, and by supplying gas (for example air) to these two chambers at a pressure below that of the gas in the pressure chamber. Each of these measurement chambers includes a wall formed with an aperture through which the cigarette rod passes to enter or leave the chamber, the aperture defining with the cigarette rod an annular orifice through which air flows at a rate dependent upon the diameter of the part of the rod lying within the aperture. This air flow produces a pressure drop, for example through a restrictor through which air is supplied to the chamber, so that the pressure in each measurement chamber is indicative of the diameter of the rod. The difference in pressure between the two low-pressure measurement chambers is indicative of the reduction in cross-sectional area caused by the air pressure in the high-pressure chamber.

It should be appreciated that the present invention does not provide a means merely of measuring the rod cross-section or diameter. Slight variations in diameter are permissible so long as the feel of the cigarette is right. This invention makes possible the direct control of the feel, that is to say the firmness of the tobacco filling of the cigarette rod.

Examples of tobacco filling indicators according to this invention are shown in the accompanying drawings. In these drawings:

FIG. 1 is a longitudinal section through one simple form of filling indicator;

FIG. 2 is a longitudinal section through a different indicator;

FIG. 3 is a longitudinal section through a third indicator; and

FIG. 4 is a section on the line IV-IV in FIG. 3.

The filling indicator shown diagrammatically in FIG. I includes a tube 2 defining firstly a pressure chamber 4 including end walls 6 and 8. The cigarette rod 10 passes through circular openings in the end walls 6 and 8 and is completely surrounded by gas in the pressure chamber 4. Air or some other gas is supplied continuously to the pressure chamber through a pipe 12. The air pressure is preset at the lower limit of cigarette filling pressure which is considered desirable in the cigarette, e.g. say 7.5 centimeters of mercury gauge or higher.

In addition to the pressure chamber 4 there are two chambers l4 and 16 connected by pipes 18 and 20 to a manifold (not shown) containing gas, for example air, at a lower pressure of say 3,8 cm. of mercury gauge. The chambers 14 and 16 are respectively precompression and postcompression chambers in that the rod 10 passes through them (in the direction of the arrow) respectively before and after being compressed in the chamber 4. Each of the air inlet pipes 18 and 20 has a restrictor 22 or 23 so that there is a pressure drop across the restrictor of an amount dependent upon the rate of gas flow through the restrictor.

In use, air flows into the chambers 14 and 16 through the pipes 18 and 20, and out through the annular outlet orifices between the rod and the apertures in the surrounding walls 24, 26, 28 and 30 of the chambers 14 and 16. The rate of flow is determined in each case by the restriction to flow imposed by the outlet orifice. In other words, the rate of flow and consequently the pressure drop through the restrictor increases as the rod diameter decreases, and conversely decreases as the rod diameter increases. A comparator device 32, for example a differential pressure transducer, is connected to the chambers 14 and 16 through pipes 34, 35 and reacts to the pressures in the chambers 14 and 16 through pipes 34, 35 and reacts to the pressures in the chambers 14 and 16. When the comparator device 32 signals a difference between the pressures in the chambers 14 and 16, it is an indication that the portion of the cigarette rod occupying chamber 16 has been deformed in its passage through chamber 4. When the differential pressure exceeds a predetermined level, the transducer activates an ejector which ejects the cigarette cut from the faulty part of the rod.

As an example, the comparator device 32 may be in the form of a pressure-balanced diaphragm carrying one or more switch contacts which cooperate with one or more fixed contacts to operate an ejector mechanism 33 when the diaphragm is displaced sufficiently by the action of a pressure differential across the diaphragm, opposite sides of the diaphragm being in communication with the chambers 14 and 16 respectively. This arrangement may be similar to that described in British Pat. Nos. 888,478 or 918,843. Alternatively the comparator may include a delayed action device so as to make comparisons always in relation to the same part of the cigarette rod.

One form of comparator which may be used comprises two spaced coaxial diaphragms joined by a member which forms or carries a part forming a movable core for an electrical inductance or transformer, the outer faces of the two diaphragms being exposed respectively to the pressures transmitted by the pipes 34 and 35 leading from the measuring chambers. This enables an electrical output signal to be obtained by means of the inductance or transformer, the value of the signal being dependent upon the position of the core member which in turn depends upon the relative values of the pressures in the two measuring chambers.

There may alternatively be a common air supply to the three pipes 12, 18 and 20. If the openings in the end walls of the chambers 14 and 16 are of the same diameter and the restrictors in the inlet pipes are the same, the pressure in the chambers 14 and 16 will always be lower than that in chamber 4 which carries the full supply pressure, as there is no restrictOl'.

In order to maintain a substantially constant pressure in the gas entering the pipes 18 and 20, the manifold from which gas flows into the pipes 18 and 20 should be of relatively large volume, so that fluctuations in the rate of flow do not produce significant fluctuations in the inlet pressure. Conversely the volumes of the chambers 14 and 16 should be small to accentuate the pressure fluctuations in them caused by flow variations. It will be appreciated that FIG. 1 is diagrammatic, and that the inner diameters of the chambers 14 and 16 should in fact be not much greater than the cigarette rod diameter.

Instead of being separate, the three chambers 4, 14 and 16 may be formed within a single tubular casing. In this case the end walls dividing the casing into the appropriate separate chambers may be formed by removable thin washers spaced and sealed by rubber O-rings. This would enable different washers with different hole diameters to be used in the manufacture of cigarette rod of differing diameters. Moreover, it would then be possible to use difi'erent washers for the chambers l4 and 16 and to vary the ratio of hole diameters in any desired fashion.

In order to achieve the same manner of operation as the arrangement shown in the drawing, this modified construction may have two washers between each adjacent pair of chambers, corresponding to the end walls 6 and 28 (or 8 and 26), with a chamber between the two washers which is freely vented to atmosphere. In principle, however, the invention may be performed by means of a modified comparator arrangement including just one washer between each adjacent pair of chambers (that is, with no intervening vented chamber); in this case gas flowing from the pressure chamber, around the cigarette rod, passes into the low-pressure chambers l4 and I6 and leaves these chambers through the pipes 18 and 20. Gas also leaves the chambers 14 and 16 through the end wall washers 24 and 30, but the arrangement may be such that this gas flow is considerably less than that through the pipes 18 and 20. The pressure in either chamber 14 or 16 in this case decreases as the cigarette rod diameter increases and vice versa.

In place of the measuring chambers 14 and 16 it is in principle possible to use two diameter measuring devices such as the described in British Pat. No. 888,478 or No. 918,843.

As a further alternative the chambers 14 and 16 may be omitted, and the comparison of precompression and postcompression rod diameters may be achieved by some other means of comparing the flow rates out of the end walls 6 and 8. For example, the apertures in the end walls may each be shaped as a venturi in the throat of which a pressure tapping is taken. The pressure in the venturi throat varies inversely with the rod diameter since a decrease in the rod diameter increases the air velocity through the venturi and vice versa. FIG. 2 of the accompanying drawings shows an example of this construction.

As shown in FIG. 2, the cigarette rod 40 passes through a pressure chamber 42 within a hollow tubular body 44, the entry apertures being defined by two similar venturi members 46 and 48 which have threaded ends 50 and 52 screwed into the body 44, with sealing rings 45. The bore in each venturi member diverges in each direction away from a throat zone 54 or 56 which, in the example shown, is of constant diameter for an axial extent slightly greater than the diameter. Pressure tapping pipes 58 and 60 lead through radial bores 62 and 64 into the venturi throats, while compressed air, for example at 7.5 centimeters of mercury gauge, is supplied to the pressure chamber through a pipe 66.

In the arrangement shown there is only one pressure tapping in each venturi throat. This depends on the cigarette rod being centralized in the venturis by the air flow. As an alternative each venturi may have a number of tappings (for example four at intervals around the venturi axis) all connected to give an average signal to the pressure transducer (not shown). A further possibility is that each venturi throat may be formed with a circumferential groove in its throat, the pressure tapping being in communication with the groove.

In the example shown in FIG. 2 the inner end of each venturi member may extend some way into the pressure chamber and may have a sharp orifice edge to drop the pressure of air flowing out of the pressure chamber through the venturis. The gradual tapering of each venturi bore to the throat may start from the sharp edge.

In the FIG. 2 arrangement, in the case of cigarettes of which the fillers have deliberately dense ends the distance between the venturi tapping bores 62 and 64 may equal the length of the cigarettes which are subsequently cut from the rod.

In order to smooth out the Flow of compressed air into the compression chamber 42 in FIG. 2, there may for example be one or more layers of wire mesh across the chamber, through which air from the inlet 66 flows before it reaches the rod. Below the mesh there may be a tapping connected to a pressure gauge to indicate the air pressure around the rod.

The bore in each venturi member may in principle be substantially of constant diameter, though it should preferably open out towards the inner end in the case of the venturi member 48 and towards the outer end in the case of the ventu ri member 46 in order to give an appropriate lead in for the rod.

A comparator, for example for use with the FIG. 2 device may be a tluidics type of device comprising a block with one passageway which is intersected by a lateral passageway to opposite ends of which the pipes 60 and 58 are connected. Compressed air is blown continuously through the first passageway and may be delivered from the pressure chamber (for example from an outlet in the end cap at the end remote from the inlet 66) or from the same source. When a slightly squashed part of the cigarette rod passages through the venturi member 48, that is to say a part of the rod which is inadequately filled, the reduced pressure in the pipe 60 allows the air in the pipe 58 to deflect the flow in the first passageway momentarily into a bypass passageway which extends from the junction of the first two passageways at an appropriate slight inclination to the first passageway. This momentary flow in the bypass passageway may be used to operate an ejector mechanism for ejecting the faulty cigarette cut subsequently from the squashed part of the rod. Alternatively the bypass passageway may be connected to a nozzle situated in a position such that the puff of air through the bypass passageway itself blows the faulty cigarette laterally out of the cigarette stream.

FIGS. 3 and 4 show a different indicator which in principle is similar to that shown in FIG. 1. Parts corresponding to those in FIG. 1 have the same reference numerals.

The three chambers 4, 14 and 16 in FIG. 3 are all within a tubular member 70 and are separated by stacks of washers 72 and 74. Each of these stacks is formed by alternating washers of different construction; in each stack the outer washers and three inner washers are plain metal washers, while the intervening washers (shown diagrammatically simply as washers of greater thickness) are washers or other members which can space apart the successive plain washers while allowing air to flow radially outwards between the plain washers and out through slots 76 in the tubular member 70. The parts between the plain washers may for example be like lock washers with slightly twisted radial teeth, or may have a circumferentially undulating form.

The outer ends of the chambers 14 and 16 are defined respectively by walls 24 and 30 each of which consists of two plain washers spaced apart by a middle washer which is like the twisted tooth or equivalent washers in the stacks 72 and 74. Accordingly air can leak out of the chambers 14 to 16 in the same way as in FIG. 1, the amount of air flow (and consequently the pressure drop through the restrictor 22 or 23) being dependent on the cross-sectional area of the relevant part of the rod 10. Air is supplied by a pipe 78 to all three chambers, the pressure drop through the restrictors l8 and being sufiicient to provide the required relatively low mean pressures in the chambers 14 and 16. The pressure in the chamber 4 is indicated by a gauge 80.

Each of the measuring chambers contains a ring 82 or 84 to which the associated pipes 18 and 34 or 20 and 35 are connected. This arrangement enables the distance between the mid points of the chambers 14 and 16 to be varied by replacing spacer sleeves 86 and 88 with sleeves of different length; preferably in use this distance is made equal to one cigarette rod length. The assembly is completed by screw-threaded plugs 100 and 102 and by six O-rings (i.e. sealing rings) as shown.

It will be appreciated that the inner diameter of the plain washers provides a clearance fit around the cigarette rod to allow the necessary air leakage from the chambers 14 and 16. The inner diameter of the twisted tooth or equivalent washers may be larger so as to be quite clear of the surface of the rod.

Leakage of air between the plain washers and out through the slots 76 ensures that air cannot flow from the pressure chamber 4 and into either measuring chamber. In other words, the multiple-washer stacks 72 and 74 effectively isolate the pressure chamber from the measuring chambers.

Each apparatus already described is in what may be termed an on-line arrangement in that a continuous cigarette rod is intended to pass axially through it. As an alternative, apparatus according to this invention may in principle be arranged to receive cut cigarettes moving side ways, for example in flutes in a carrier drum. In this case the cigarette carrier and a closure member may, at a suitable testing point, define a series of axially spaced chambers around each cigarette connected alternately to pressure (through restrictors) and atmosphere, with transducer tappings to the pressure chambers; the transducer arrangement may, for example, compare the pressure in an end pressure chamber around the densely filled part of the cigarette (taken as a datum) with each of the other pressures. The carrier and closure members may both be fluted drums rotating side by side, the testing point being between the drums.

A machine or method according to the invention may include provision for detecting the degree of moisture in the tobacco and for compensating for any deviation from the average figure in so far as the moisture may effect the firmness of the cigarette rod. In other words, in the case of a tobacco filling which is, for example, less firm while moist and becomes more firm when the moisture later evaporates, the moisture compensating system may be arranged, for example, to lower the firmness level below which signals from the comparator system cause the ejector mechanism to operate in the case of cigarettes with a much higher than average moisture content.

We claim:

1. A cigarette filling indicator comprising means for defining a pressure chamber around a continuous axially moving cigarette rod; means for supplying compressed air to the chamber around the cigarette rod tocompress slightly at least an inadequately filled rod; pressure tapping means for producing pressure signals at axially spaced positions along the rod as a result of leakage between the rod and a surrounding part of the indicator, which leakage is dependent upon the cross-sectional area of the particular part of the rod, the said pressure tapping means being situated respectively upstream and downstream of the pressure chamber in relation to movement of the rod; and a comJJarator device for comparingthe different pressures to pro uce a correction signal indicative of an inadequately filled rod portion.

2. An indicator according to claim 1 in which the pressure tappings are taken from measuring chambers which are situated respectively upstream and downstream of the pressure chamber and to which air is supplied via restrictors at a pres sure lower than that in the pressure chamber, the exact pressure in each measuring chamber at any given moment being dependent upon the level of air leakage from that measuring chamber which in turn depends upon the cross-sectional area of the rod in that region.

3. An indicator according to claim 2 in which the pressure chamber and the two measuring chambers are all within a tubular member along the axis of which the rod is arranged to pass.

4. An indicator according to claim 3 in which the pressure chamber is isolated from each of the measuring chambers by a stack of washers spaced apart so as to allow air to flow out radially between the washers and through an opening in the wall of the tubular member.

5. An indicator according to claim 4 in which the opening comprises at least one slot through which pipes extend which respectively supply air to the measuring chamber and serve as the pressure tapping, so that the position of the measuring chamber along the tubular member can be varied.

6. An indicator according to claim 1 in which the pressure tappings are respectively at the throat regions of two venturi or venturilike openings in the pressure chamber through which the rod passes during use.

7. An indicator according to claim 1 in which the comparator device is a diaphragm transducer.

8. A cigarette making machine including a filling pressure indicator according to claim 1 and a device which, in response to correction signals from the comparator device, ejects cigarettes cut from parts of the rod which are inadequately filled.

9. A cigarette-making machine comprising means for forming a continuous cigarette rod; means cutting the continuous rod into cigarette lengths; means for ejecting unsatisfactory cigarette lengths; and testing means mounted ahead of the cutting means for testing the filling pressure of the rod; said testing means comprising a pressure chamber mounted in line with the continuous rod and having end walls formed with openings through which the rod passes, two measuring means positioned respectively upstream and downstream of the pressure chamber and sensitive respectively to the cross-sectional area of the rod before and after it passes through the pressure chamber, and comparator means connected to the said measuring means for operating the said cigarette ejector means when the difference between the signals from the two measuring means is above a predetermined level. 

1. A cigarette filling indicator comprising means for defining a pressure chamber around a continuous axially moving cigarette rod; means for supplying compressed air to the chamber around the cigarette rod to compress slightly at least an inadequately filled rod; pressure tapping means for producing pressure signals at axially spaced positions along the rod as a result of leakage between the rod and a surrounding part of the indicator, which leakage is dependent upon the cross-sectional area of the particular part of the rod, the said pressure tapping means being situated respectively upstream and downstream of the pressure chamber in relation to movement of the rod; and a comparator device for comparing the different pressures to produce a correction signal indicative of an inadequately filled rod portion.
 2. An indicator according to claim 1 in which the pressure tappings are taken from measuring chambers which are situated respectively upstream and downstream of the pressure chamber and to which air is supplied via restrictors at a pressure lower than that in the pressure chamber, the exact pressure in each measuring chamber at any given moment being dependent upon the level of air leakage from that measuring chamber which in turn depends upon the cross-sectional area of the rod in that region.
 3. An indicator according to claim 2 in which the pressure chamber and the two measuring chambers are all within a tubular member along the axis of which the rod is arranged to pass.
 4. An indicator according to claim 3 in which the pressure chamber is isolated from each of the measuring chambers by a stack of washers spaced apart so as to allow air to flow out radially between the washers and through an opening in the wall of the tubular member.
 5. An indicator according to claim 4 in which the opening comprises at least one slot through which pipes extend which respectively supply air to the measuring chamber and serve as the pressure tapping, so that the position of the measuring chamber along the tubular member can be varied.
 6. An indicator according to claim 1 in which the pressure tappings are respectively at the throat regions of two venturi or venturilike openings in the pressure chamber through which the rod passes during use.
 7. An indicator according to claim 1 in which the comparator device is a diaphragm transducer.
 8. A cigarette making machine including a filling pressure indicator according to claim 1 and a device which, in response to correction signals from the comparator device, ejects cigarettes cut from parts of the rod which are inadequately filled.
 9. A cigarette-making machine comprising means for forming a continuous cigarette rod; means cutting the continuous rod into cigarEtte lengths; means for ejecting unsatisfactory cigarette lengths; and testing means mounted ahead of the cutting means for testing the filling pressure of the rod; said testing means comprising a pressure chamber mounted in line with the continuous rod and having end walls formed with openings through which the rod passes, two measuring means positioned respectively upstream and downstream of the pressure chamber and sensitive respectively to the cross-sectional area of the rod before and after it passes through the pressure chamber, and comparator means connected to the said measuring means for operating the said cigarette ejector means when the difference between the signals from the two measuring means is above a predetermined level. 